[thirdparty/linux.git] / fs / kernfs / inode.c

/*
 * fs/kernfs/inode.c - kernfs inode implementation
 *
 * Copyright (c) 2001-3 Patrick Mochel
 * Copyright (c) 2007 SUSE Linux Products GmbH
 * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
 *
 * This file is released under the GPLv2.
 */

#include <linux/pagemap.h>
#include <linux/backing-dev.h>
#include <linux/capability.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/xattr.h>
#include <linux/security.h>

#include "kernfs-internal.h"

static const struct address_space_operations sysfs_aops = {
	.readpage	= simple_readpage,
	.write_begin	= simple_write_begin,
	.write_end	= simple_write_end,
};

static struct backing_dev_info sysfs_backing_dev_info = {
	.name		= "sysfs",
	.ra_pages	= 0,	/* No readahead */
	.capabilities	= BDI_CAP_NO_ACCT_AND_WRITEBACK,
};

static const struct inode_operations sysfs_inode_operations = {
	.permission	= sysfs_permission,
	.setattr	= sysfs_setattr,
	.getattr	= sysfs_getattr,
	.setxattr	= sysfs_setxattr,
};

void __init sysfs_inode_init(void)
{
	if (bdi_init(&sysfs_backing_dev_info))
		panic("failed to init sysfs_backing_dev_info");
}

static struct sysfs_inode_attrs *sysfs_init_inode_attrs(struct sysfs_dirent *sd)
{
	struct sysfs_inode_attrs *attrs;
	struct iattr *iattrs;

	attrs = kzalloc(sizeof(struct sysfs_inode_attrs), GFP_KERNEL);
	if (!attrs)
		return NULL;
	iattrs = &attrs->ia_iattr;

	/* assign default attributes */
	iattrs->ia_mode = sd->s_mode;
	iattrs->ia_uid = GLOBAL_ROOT_UID;
	iattrs->ia_gid = GLOBAL_ROOT_GID;
	iattrs->ia_atime = iattrs->ia_mtime = iattrs->ia_ctime = CURRENT_TIME;

	return attrs;
}

static int __kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr)
{
	struct sysfs_inode_attrs *sd_attrs;
	struct iattr *iattrs;
	unsigned int ia_valid = iattr->ia_valid;

	sd_attrs = sd->s_iattr;

	if (!sd_attrs) {
		/* setting attributes for the first time, allocate now */
		sd_attrs = sysfs_init_inode_attrs(sd);
		if (!sd_attrs)
			return -ENOMEM;
		sd->s_iattr = sd_attrs;
	}
	/* attributes were changed at least once in past */
	iattrs = &sd_attrs->ia_iattr;

	if (ia_valid & ATTR_UID)
		iattrs->ia_uid = iattr->ia_uid;
	if (ia_valid & ATTR_GID)
		iattrs->ia_gid = iattr->ia_gid;
	if (ia_valid & ATTR_ATIME)
		iattrs->ia_atime = iattr->ia_atime;
	if (ia_valid & ATTR_MTIME)
		iattrs->ia_mtime = iattr->ia_mtime;
	if (ia_valid & ATTR_CTIME)
		iattrs->ia_ctime = iattr->ia_ctime;
	if (ia_valid & ATTR_MODE) {
		umode_t mode = iattr->ia_mode;
		iattrs->ia_mode = sd->s_mode = mode;
	}
	return 0;
}

/**
 * kernfs_setattr - set iattr on a node
 * @sd: target node
 * @iattr: iattr to set
 *
 * Returns 0 on success, -errno on failure.
 */
int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr)
{
	int ret;

	mutex_lock(&sysfs_mutex);
	ret = __kernfs_setattr(sd, iattr);
	mutex_unlock(&sysfs_mutex);
	return ret;
}

int sysfs_setattr(struct dentry *dentry, struct iattr *iattr)
{
	struct inode *inode = dentry->d_inode;
	struct sysfs_dirent *sd = dentry->d_fsdata;
	int error;

	if (!sd)
		return -EINVAL;

	mutex_lock(&sysfs_mutex);
	error = inode_change_ok(inode, iattr);
	if (error)
		goto out;

	error = __kernfs_setattr(sd, iattr);
	if (error)
		goto out;

	/* this ignores size changes */
	setattr_copy(inode, iattr);

out:
	mutex_unlock(&sysfs_mutex);
	return error;
}

static int sysfs_sd_setsecdata(struct sysfs_dirent *sd, void **secdata,
			       u32 *secdata_len)
{
	struct sysfs_inode_attrs *iattrs;
	void *old_secdata;
	size_t old_secdata_len;

	if (!sd->s_iattr) {
		sd->s_iattr = sysfs_init_inode_attrs(sd);
		if (!sd->s_iattr)
			return -ENOMEM;
	}

	iattrs = sd->s_iattr;
	old_secdata = iattrs->ia_secdata;
	old_secdata_len = iattrs->ia_secdata_len;

	iattrs->ia_secdata = *secdata;
	iattrs->ia_secdata_len = *secdata_len;

	*secdata = old_secdata;
	*secdata_len = old_secdata_len;
	return 0;
}

int sysfs_setxattr(struct dentry *dentry, const char *name, const void *value,
		size_t size, int flags)
{
	struct sysfs_dirent *sd = dentry->d_fsdata;
	void *secdata;
	int error;
	u32 secdata_len = 0;

	if (!sd)
		return -EINVAL;

	if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) {
		const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
		error = security_inode_setsecurity(dentry->d_inode, suffix,
						value, size, flags);
		if (error)
			goto out;
		error = security_inode_getsecctx(dentry->d_inode,
						&secdata, &secdata_len);
		if (error)
			goto out;

		mutex_lock(&sysfs_mutex);
		error = sysfs_sd_setsecdata(sd, &secdata, &secdata_len);
		mutex_unlock(&sysfs_mutex);

		if (secdata)
			security_release_secctx(secdata, secdata_len);
	} else
		return -EINVAL;
out:
	return error;
}

static inline void set_default_inode_attr(struct inode *inode, umode_t mode)
{
	inode->i_mode = mode;
	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
}

static inline void set_inode_attr(struct inode *inode, struct iattr *iattr)
{
	inode->i_uid = iattr->ia_uid;
	inode->i_gid = iattr->ia_gid;
	inode->i_atime = iattr->ia_atime;
	inode->i_mtime = iattr->ia_mtime;
	inode->i_ctime = iattr->ia_ctime;
}

static void sysfs_refresh_inode(struct sysfs_dirent *sd, struct inode *inode)
{
	struct sysfs_inode_attrs *iattrs = sd->s_iattr;

	inode->i_mode = sd->s_mode;
	if (iattrs) {
		/* sysfs_dirent has non-default attributes
		 * get them from persistent copy in sysfs_dirent
		 */
		set_inode_attr(inode, &iattrs->ia_iattr);
		security_inode_notifysecctx(inode,
					    iattrs->ia_secdata,
					    iattrs->ia_secdata_len);
	}

	if (sysfs_type(sd) == SYSFS_DIR)
		set_nlink(inode, sd->s_dir.subdirs + 2);
}

int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
		  struct kstat *stat)
{
	struct sysfs_dirent *sd = dentry->d_fsdata;
	struct inode *inode = dentry->d_inode;

	mutex_lock(&sysfs_mutex);
	sysfs_refresh_inode(sd, inode);
	mutex_unlock(&sysfs_mutex);

	generic_fillattr(inode, stat);
	return 0;
}

static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
{
	kernfs_get(sd);
	inode->i_private = sd;
	inode->i_mapping->a_ops = &sysfs_aops;
	inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
	inode->i_op = &sysfs_inode_operations;

	set_default_inode_attr(inode, sd->s_mode);
	sysfs_refresh_inode(sd, inode);

	/* initialize inode according to type */
	switch (sysfs_type(sd)) {
	case SYSFS_DIR:
		inode->i_op = &sysfs_dir_inode_operations;
		inode->i_fop = &sysfs_dir_operations;
		break;
	case SYSFS_KOBJ_ATTR:
		inode->i_size = sd->s_attr.size;
		inode->i_fop = &kernfs_file_operations;
		break;
	case SYSFS_KOBJ_LINK:
		inode->i_op = &sysfs_symlink_inode_operations;
		break;
	default:
		BUG();
	}

	unlock_new_inode(inode);
}

/**
 *	sysfs_get_inode - get inode for sysfs_dirent
 *	@sb: super block
 *	@sd: sysfs_dirent to allocate inode for
 *
 *	Get inode for @sd.  If such inode doesn't exist, a new inode
 *	is allocated and basics are initialized.  New inode is
 *	returned locked.
 *
 *	LOCKING:
 *	Kernel thread context (may sleep).
 *
 *	RETURNS:
 *	Pointer to allocated inode on success, NULL on failure.
 */
struct inode *sysfs_get_inode(struct super_block *sb, struct sysfs_dirent *sd)
{
	struct inode *inode;

	inode = iget_locked(sb, sd->s_ino);
	if (inode && (inode->i_state & I_NEW))
		sysfs_init_inode(sd, inode);

	return inode;
}

/*
 * The sysfs_dirent serves as both an inode and a directory entry for sysfs.
 * To prevent the sysfs inode numbers from being freed prematurely we take a
 * reference to sysfs_dirent from the sysfs inode.  A
 * super_operations.evict_inode() implementation is needed to drop that
 * reference upon inode destruction.
 */
void sysfs_evict_inode(struct inode *inode)
{
	struct sysfs_dirent *sd  = inode->i_private;

	truncate_inode_pages(&inode->i_data, 0);
	clear_inode(inode);
	kernfs_put(sd);
}

int sysfs_permission(struct inode *inode, int mask)
{
	struct sysfs_dirent *sd;

	if (mask & MAY_NOT_BLOCK)
		return -ECHILD;

	sd = inode->i_private;

	mutex_lock(&sysfs_mutex);
	sysfs_refresh_inode(sd, inode);
	mutex_unlock(&sysfs_mutex);

	return generic_permission(inode, mask);
}
Commit	Line	Data
b8441ed2 TH	1	/*
	2	* fs/kernfs/inode.c - kernfs inode implementation
	3	*
	4	* Copyright (c) 2001-3 Patrick Mochel
	5	* Copyright (c) 2007 SUSE Linux Products GmbH
	6	* Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
	7	*
	8	* This file is released under the GPLv2.
	9	*/
ffed24e2 TH	10
	11	#include <linux/pagemap.h>
	12	#include <linux/backing-dev.h>
	13	#include <linux/capability.h>
	14	#include <linux/errno.h>
	15	#include <linux/slab.h>
	16	#include <linux/xattr.h>
	17	#include <linux/security.h>
	18
	19	#include "kernfs-internal.h"
	20
	21	static const struct address_space_operations sysfs_aops = {
	22	.readpage = simple_readpage,
	23	.write_begin = simple_write_begin,
	24	.write_end = simple_write_end,
	25	};
	26
	27	static struct backing_dev_info sysfs_backing_dev_info = {
	28	.name = "sysfs",
	29	.ra_pages = 0, /* No readahead */
	30	.capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
	31	};
	32
	33	static const struct inode_operations sysfs_inode_operations = {
	34	.permission = sysfs_permission,
	35	.setattr = sysfs_setattr,
	36	.getattr = sysfs_getattr,
	37	.setxattr = sysfs_setxattr,
	38	};
	39
4b93dc9b	40	void __init sysfs_inode_init(void)
ffed24e2	41	{
4b93dc9b TH	42	if (bdi_init(&sysfs_backing_dev_info))
4b93dc9b TH	43	panic("failed to init sysfs_backing_dev_info");
ffed24e2 TH	44	}
	45
	46	static struct sysfs_inode_attrs sysfs_init_inode_attrs(struct sysfs_dirent sd)
	47	{
	48	struct sysfs_inode_attrs *attrs;
	49	struct iattr *iattrs;
	50
	51	attrs = kzalloc(sizeof(struct sysfs_inode_attrs), GFP_KERNEL);
	52	if (!attrs)
	53	return NULL;
	54	iattrs = &attrs->ia_iattr;
	55
	56	/* assign default attributes */
	57	iattrs->ia_mode = sd->s_mode;
	58	iattrs->ia_uid = GLOBAL_ROOT_UID;
	59	iattrs->ia_gid = GLOBAL_ROOT_GID;
	60	iattrs->ia_atime = iattrs->ia_mtime = iattrs->ia_ctime = CURRENT_TIME;
	61
	62	return attrs;
	63	}
	64
	65	static int __kernfs_setattr(struct sysfs_dirent sd, const struct iattr iattr)
	66	{
	67	struct sysfs_inode_attrs *sd_attrs;
	68	struct iattr *iattrs;
	69	unsigned int ia_valid = iattr->ia_valid;
	70
	71	sd_attrs = sd->s_iattr;
	72
	73	if (!sd_attrs) {
	74	/* setting attributes for the first time, allocate now */
	75	sd_attrs = sysfs_init_inode_attrs(sd);
	76	if (!sd_attrs)
	77	return -ENOMEM;
	78	sd->s_iattr = sd_attrs;
	79	}
	80	/* attributes were changed at least once in past */
	81	iattrs = &sd_attrs->ia_iattr;
	82
	83	if (ia_valid & ATTR_UID)
	84	iattrs->ia_uid = iattr->ia_uid;
	85	if (ia_valid & ATTR_GID)
	86	iattrs->ia_gid = iattr->ia_gid;
	87	if (ia_valid & ATTR_ATIME)
	88	iattrs->ia_atime = iattr->ia_atime;
	89	if (ia_valid & ATTR_MTIME)
	90	iattrs->ia_mtime = iattr->ia_mtime;
	91	if (ia_valid & ATTR_CTIME)
	92	iattrs->ia_ctime = iattr->ia_ctime;
	93	if (ia_valid & ATTR_MODE) {
	94	umode_t mode = iattr->ia_mode;
	95	iattrs->ia_mode = sd->s_mode = mode;
	96	}
	97	return 0;
	98	}
	99
	100	/**
	101	* kernfs_setattr - set iattr on a node
	102	* @sd: target node
	103	* @iattr: iattr to set
	104	*
	105	* Returns 0 on success, -errno on failure.
	106	*/
	107	int kernfs_setattr(struct sysfs_dirent sd, const struct iattr iattr)
108	{
109	int ret;
110
111	mutex_lock(&sysfs_mutex);
112	ret = __kernfs_setattr(sd, iattr);
113	mutex_unlock(&sysfs_mutex);
114	return ret;
115	}
116
117	int sysfs_setattr(struct dentry dentry, struct iattr iattr)
118	{
119	struct inode *inode = dentry->d_inode;
120	struct sysfs_dirent *sd = dentry->d_fsdata;
121	int error;
122
123	if (!sd)
124	return -EINVAL;
125
126	mutex_lock(&sysfs_mutex);
127	error = inode_change_ok(inode, iattr);
128	if (error)
129	goto out;
130
131	error = __kernfs_setattr(sd, iattr);
132	if (error)
133	goto out;
134
135	/* this ignores size changes */
136	setattr_copy(inode, iattr);
137
138	out:
139	mutex_unlock(&sysfs_mutex);
140	return error;
141	}
142
143	static int sysfs_sd_setsecdata(struct sysfs_dirent sd, void *secdata,
144	u32 *secdata_len)
145	{
146	struct sysfs_inode_attrs *iattrs;
147	void *old_secdata;
148	size_t old_secdata_len;
149
150	if (!sd->s_iattr) {
151	sd->s_iattr = sysfs_init_inode_attrs(sd);
152	if (!sd->s_iattr)
153	return -ENOMEM;
154	}
155
156	iattrs = sd->s_iattr;
157	old_secdata = iattrs->ia_secdata;
158	old_secdata_len = iattrs->ia_secdata_len;
159
160	iattrs->ia_secdata = *secdata;
161	iattrs->ia_secdata_len = *secdata_len;
162
163	*secdata = old_secdata;
164	*secdata_len = old_secdata_len;
165	return 0;
166	}
167
168	int sysfs_setxattr(struct dentry dentry, const char name, const void *value,
169	size_t size, int flags)
170	{
171	struct sysfs_dirent *sd = dentry->d_fsdata;
172	void *secdata;
173	int error;
174	u32 secdata_len = 0;
175
176	if (!sd)
177	return -EINVAL;
178
179	if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) {
180	const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
181	error = security_inode_setsecurity(dentry->d_inode, suffix,
182	value, size, flags);
183	if (error)
184	goto out;
185	error = security_inode_getsecctx(dentry->d_inode,
186	&secdata, &secdata_len);
187	if (error)
188	goto out;
189
190	mutex_lock(&sysfs_mutex);
191	error = sysfs_sd_setsecdata(sd, &secdata, &secdata_len);
192	mutex_unlock(&sysfs_mutex);
193
194	if (secdata)
195	security_release_secctx(secdata, secdata_len);
196	} else
197	return -EINVAL;
198	out:
199	return error;
200	}
201
202	static inline void set_default_inode_attr(struct inode *inode, umode_t mode)
203	{
204	inode->i_mode = mode;
205	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
206	}
207
208	static inline void set_inode_attr(struct inode inode, struct iattr iattr)
209	{
210	inode->i_uid = iattr->ia_uid;
211	inode->i_gid = iattr->ia_gid;
212	inode->i_atime = iattr->ia_atime;
213	inode->i_mtime = iattr->ia_mtime;
214	inode->i_ctime = iattr->ia_ctime;
215	}
216
217	static void sysfs_refresh_inode(struct sysfs_dirent sd, struct inode inode)
218	{
219	struct sysfs_inode_attrs *iattrs = sd->s_iattr;
220
221	inode->i_mode = sd->s_mode;
222	if (iattrs) {
223	/* sysfs_dirent has non-default attributes
224	* get them from persistent copy in sysfs_dirent
225	*/
226	set_inode_attr(inode, &iattrs->ia_iattr);
227	security_inode_notifysecctx(inode,
228	iattrs->ia_secdata,
229	iattrs->ia_secdata_len);
230	}
231
232	if (sysfs_type(sd) == SYSFS_DIR)
233	set_nlink(inode, sd->s_dir.subdirs + 2);
234	}
235
236	int sysfs_getattr(struct vfsmount mnt, struct dentry dentry,
237	struct kstat *stat)
238	{
239	struct sysfs_dirent *sd = dentry->d_fsdata;
240	struct inode *inode = dentry->d_inode;
241
242	mutex_lock(&sysfs_mutex);
243	sysfs_refresh_inode(sd, inode);
244	mutex_unlock(&sysfs_mutex);
245
246	generic_fillattr(inode, stat);
247	return 0;
248	}
249
250	static void sysfs_init_inode(struct sysfs_dirent sd, struct inode inode)
251	{
252	kernfs_get(sd);
253	inode->i_private = sd;
254	inode->i_mapping->a_ops = &sysfs_aops;
255	inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
256	inode->i_op = &sysfs_inode_operations;
257
258	set_default_inode_attr(inode, sd->s_mode);
259	sysfs_refresh_inode(sd, inode);
260
261	/* initialize inode according to type */
262	switch (sysfs_type(sd)) {
263	case SYSFS_DIR:
264	inode->i_op = &sysfs_dir_inode_operations;
265	inode->i_fop = &sysfs_dir_operations;
266	break;
267	case SYSFS_KOBJ_ATTR:
268	inode->i_size = sd->s_attr.size;
269	inode->i_fop = &kernfs_file_operations;
270	break;
271	case SYSFS_KOBJ_LINK:
272	inode->i_op = &sysfs_symlink_inode_operations;
273	break;
274	default:
275	BUG();
276	}
277
278	unlock_new_inode(inode);
279	}
280
281	/**
282	* sysfs_get_inode - get inode for sysfs_dirent
283	* @sb: super block
284	* @sd: sysfs_dirent to allocate inode for
285	*
286	* Get inode for @sd. If such inode doesn't exist, a new inode
287	* is allocated and basics are initialized. New inode is
288	* returned locked.
289	*
290	* LOCKING:
291	* Kernel thread context (may sleep).
292	*
293	* RETURNS:
294	* Pointer to allocated inode on success, NULL on failure.
295	*/
296	struct inode sysfs_get_inode(struct super_block sb, struct sysfs_dirent *sd)
297	{
298	struct inode *inode;
299
300	inode = iget_locked(sb, sd->s_ino);
301	if (inode && (inode->i_state & I_NEW))
302	sysfs_init_inode(sd, inode);
303
304	return inode;
305	}
306
307	/*
308	* The sysfs_dirent serves as both an inode and a directory entry for sysfs.
309	* To prevent the sysfs inode numbers from being freed prematurely we take a
310	* reference to sysfs_dirent from the sysfs inode. A
311	* super_operations.evict_inode() implementation is needed to drop that
312	* reference upon inode destruction.
313	*/
314	void sysfs_evict_inode(struct inode *inode)
315	{
316	struct sysfs_dirent *sd = inode->i_private;
317
318	truncate_inode_pages(&inode->i_data, 0);
319	clear_inode(inode);
320	kernfs_put(sd);
321	}
322
323	int sysfs_permission(struct inode *inode, int mask)
324	{
325	struct sysfs_dirent *sd;
326
327	if (mask & MAY_NOT_BLOCK)
328	return -ECHILD;
329
330	sd = inode->i_private;
331
332	mutex_lock(&sysfs_mutex);
333	sysfs_refresh_inode(sd, inode);
334	mutex_unlock(&sysfs_mutex);
335
336	return generic_permission(inode, mask);
337	}